Concrete pipe with improved bell reinforcement



Oct. 6, 1964 w. M. LAFFERTY CONCRETE PIPE WITH IMPROVED BELL REINFORCEMENT Filed May 5, 1961 III/ll! FIGJ.

I00 v I INVENTOR WYLIE M. LAFFERTY ATTORNEYS United States Patent "ce 3,151,870 CONCRETE PEPE WITH IMPROVED BELL REINFORCEMENT Wylie M. Lafterty, New Philadelphia, Ohio, assignor to United States Concrete Pipe Company, Pittsburgh, Fa,

a company of Pennsylvania Filed May 3, 1961, Ser. No. 107,411 8 Claims. (Cl. 277237) This invention relates generally to bell and spigot concrete pipe and has specific reference to a tamped concrete pipe'having reinforced bell ends.

Bell and spigot concrete pipe is formed as a unitary structure having spigot and bell ends. The spigot end has an interior wall which has the same diameter as the shank or body of the pipe, and an exterior wall, which has the same diameter as the pipe shank or which may be tapered. The bell end has interior and exterior diameters, which are larger-than those of the spigot end, so that when the spigot end of an adjacent pipe is disposed within the bell end, as the pipe sections are assembled together the joint therebetween permits for substantially uninterrupted fluid flow within thepipe, by precluding the necessity of constricting the interior pipe diameter at the joint. When the exterior wall of the spigot end is tapered the interior or the bell end is tapered complementary thereto.

The interior diameter of the bell end of the pipe is, therefore, greater than the interior diameter of the pipe shank by an amount equal to or slightly greater than twice the thickness of the pipe wall at the spigot end and the exterior diameter of the bell end is sufficiently large to provide a bell end wall having the desired structural strength.

For years it' has been common to produce cast bell and spigot concrete .pipe by using suitable metal, wooden or other forms, pouring the concrete therein, allowing suffi- .cient time, up to.24 hours or more, for the concrete to set and then removing the pipe from the forms and permitting it to cure.

This process requires that the forms be used continuously for a period of 24 hours or more to produce a single length or section of pipe and a great many forms are necessary, therefore, in order to manufacture a relatively few sections of pipe. The process is, accordingly, slow and expensive in use andpractice. The shank of cast concrete pipe could be and frequently was reinforced along its length by wire mesh or other means.

Subsequently, it has become more common to provide tamped concrete pipe.

Tamped bell and spigot concrete pipe is also produced by the use of molds or forms of suitable size, shape and material. This process, however, utilizes an extremely viscous concrete slurry, having only about 6 percent moisture, or just slightly more than that necessary for hydration of the concrete. As the viscous concrete slurry is poured into the form, it is repeatedly tamped or impacted, automatically, by mechanical means, so as to compact the concrete to increase its density and thereby its strength and utility.

With tamped concrete pipe the forms may be removed substantially immediately upon completion of the pouring, as the concrete sets at once, using substantially all of the moisture present in the slurry to hydrate and the newly formed concrete pipe immediately has sufficient strength to maintain its own shape and form while curing even though unsupported by the forms necessary for pouring.

Tamped concrete pipe has also been customarily manufactured with reinforcing wire or mesh in the spigot end and pipe shank.

However, production problems, incident to forming the 3,151 ,870 Patented Get. 6, 1964 bell end of tamped concrete pipe have effectively precluded providing satisfactory metal reinforcement for the bell ends. Accordingly, it has been common to strengthen the bell end of concrete pipe by making the walls thereof of greater thickness than the Walls of the pipe section generally and of the spigot end in particular.

This has not been entirely successful, however, and the bell end of a concrete pipe section has been the Weak portion of the structure. Pipe failures and breakage, both during and after installation, have occurred more frequently at the bell end than at any other part of the pipe section.

Accordingly, it has been found desirable to provide bell and spigot concrete pipe having reinforced bell ends, but the apparatus and method commonly used for manufacturing tamped bell and spigot concrete pipe is such that reinforcement of the bell end has precluded proper tamping and compacting the bell, particularly laterally exteriorly of the reinforcement and especially when, as is desirable, the reinforcement comprises a solid metallic cylinder disposed substantially intermediate the thickness of the bell end wall.

Therefore, a primary object is to provide a new and improved reinforced bell and spigot concrete pipe.

Other objects and advantages of this invention will become apparent in the specification, claims, and accompanying drawings, wherein:

FIGURE 1 shows a section of a pipe having mated bell and spigot ends reinforced according to this invention, and

FIGURE 2 shows a section of a pipe having mated bell and spigot ends reinforced according to a modification of this invention.

It has been customary in the past, when forming reinforced tamped concrete pipe to terminate the wire mesh reinforcement 2 3 short of the bell end of the pipe so that a bell packer can form the bell. Recently it has been found desirable, as pointed out above, to provide also a metal reinforcement in the bell end of the pipe.

Of necessity, this reinforcement is offset radially from, and has a larger diameter than, the reinforcement 2%, which extends longitudinally through the spigot and shank of the pipe. Such reinforcement is indicated at 44, in FIGURES 1 and 2, and preferably comprises a solid meand exterior diameters of the bell end of the pipe section.

In FIGURE 1, the bell end is shown in engagement with the spigot end 82 of an adjacent concrete pipe made according to the present invention.

Referring first to the spigot end 82 of the pipe in FIG- URE 1, there is provided circumferential recess 84 extending therearound. The wire mesh 20 is shown to be reinforced by longitudinally extending bars 86. Additionally, there are provided longitudinally extending bars 87 in engagement with the outer surface of the Wire mesh 20. The end surface 88 of the spigot end 82 of the pipe is shown to be smoothly curved adjacent the outer side wall, thence inwardly tapered, to allow for a slight misalignment of fit. In this regard, the outside wall 90 of the spigot end 82 is of lesser diameter than the inside wall 92 of the bell end Si). Mounted within the circumferential recess 84 is an O-ring 94 of resilient material, the O-ring being shown as deformed by virtue of the engagement of the joint, to substantially fill the recess 84.

The bell end 80 of the pipe is provided with an annular reinforcing ring 44, as previously described. The annular reinforcing ring 44 has a plurality of apertures 96 spaced therearound. In this regard, the provision of the apertures 96 allows for an even distribution of concrete from one side of the ring 44 to the other side when the bell end 80 is subjected to a roller tamping force. Thus, a

structure of relatively even composition is provided at the bell end 82, as is apparent. The bell end, however, is of greater density than the remaining length of the pipe.

In FIGURE 1, the bottom end of the ring 44 is joined to the longitudinal rods 86 adjacent the reinforcing screen 20 by spaced apart transition rods 98 welded at one end to the bottom by ring 44 and at the other end by a rod 86. Such an arrangement provides for an enhanced support for the ring 44 during the sequence of forming the reinforced bell end structure. However, the transition rods 98 maybe omitted if desired. Additionally, the inside wall 92 may extend straight instead of having the provision of an outwardly tapered portion 100 extending circumferentially about the inner end of the spigot end 80. Such a tapered portion 100 facilitates engagement of the spigot end 82 therewith.

Turning now to FIGURE 2, still a further modification of the structure is shown. There is provided a second reinforcing screen 20 supported by longitudinal rods 86 disposed about the inner screen 20 in spaced apart concentric relationship. The annular reinforcing ring 44 is secured to the end of the screen 20' and rods 86' in counterdistinction to the provision of the transition rods 98 in FIGURE 1.

Further, the longitudinal rod 87 is longitudinally displaced from the end 88 of the spigot end 82 of the pipe. Further, the peripheral structure of the bell end 80 of the pipe is modified to provide a continuous surface, as compared to the conventional outwardly tapered portion shown in FIGURE 1.

By virtue of the configuration of the concrete pipe structures in FIGURES 1 and 2, there is provided concrete pipe with bell end structures which are of notably superior strength. The provision of a deformable O-ring in the recessed portion 84 of the spigot end 82, together with the configuration of the ends 88 of the spigot end 82, and the spaced apart relationship between the engaging surfaces, provides a notably improved joint structure, which allows for slight misalignment while retaining the essential feature of a strong joint capable of withstanding excessive stresses.

Those skilled in the art will appreciate that various changes and modifications can be made to the invention herein described and disposed without departing from the spirit and scope thereof. The essential features of the invention are defined in the appended claims.

I claim:

1. Concrete pipe comprising: a bell end and a spigot end, said spigot end including a circumferential recess extending about the outside recess thereof; a deformable O-ring carried in said recess for engagement with the inside surface of the bell end of an adjacent pipe; said bell end including a solid metallic cylinder spaced intermediate the inside and outside walls thereof.

2. Structure according to claim 1 wherein the bell end of said pipe is of a greater density than the remaining length thereof.

3. Structure according to claim 1 wherein the inside surface of said bell end is spaced apart from the outside surface of said spigot end to provide a space for deformation of the O-ring when engaged with an adjacent pipe.

4. Structure according to claim 1 wherein said circumferential recess is generally rectangular.

5. Structure according to claim 1 wherein the end surface of the spigot end of said pipe is inwardly tapered from the outside wall to the inside wall thereof.

6. Structure according to claim 1 wherein said cylinder includes spaced apart apertures therethrough.

7. Concrete pipe comprising: a bell end and a spigot end, said spigot end including a circumferential recess extending about the outside recess thereof; a deformable O-ring carried in said recess for engagement with the inside surface of the bell end of an adjacent pipe; said bell end including an annular reinforcing ring spaced intermediate the inside and outside walls thereof, wherein said pipe includes reinforcing means spaced intermediate the inside and outside wall thereof; and transition rod means securing said reinforcing ring to said reinforcing means.

8. Concrete pipe comprising: a bell end and a spigot end, said spigot end including a circumferential recess extending about the outside recess thereof; a deformable O-ring carried in said recess for engagement with the inside surface of the bell end of an adjacent pipe; said bell end including an annular reinforcing ring spaced intermediate the inside and outside walls thereof, wherein said pipe includes first and second reinforcing means spaced intermediate the inside and outside walls thereof in concentric relationship; said reinforcing ring being joined to the upper end of said outer reinforcing means.

References Cited in the file of this patent UNITED STATES PATENTS 1,475,150 Sweney Nov. 20, 1923 1,976,589 Trickey Oct. 9, 1934 2,296,560 MacKennon Sept. 22, 1942 2,306,496 Petersen Dec. 29, 1942 2,356,852 Hutchinson Aug. 29, 1944 2,602,469 Whiting July 8, 1952 2,698,193 Kennison Dec. 28, 1954 2,707,003 Kennison Apr. 26, 1955 2,712,679 Everhart et a1. July 12, 1955 2,722,438 Kennison Nov. 1, 1955 2,863,205 Seaman et a1. Dec. 9, 1958 2,929,124 James Mar. 22, 1960 FOREIGN PATENTS 1,258,351 France Mar. 6, 1961 

1. CONCRETE PIPE COMPRISING: A BELL END AND A SPIGOT END, SAID SPIGOT END INCLUDING A CIRCUMFERENTIAL RECESS EXTENDING ABOUT THE OUTSIDE RECESS THEREOF; A DEFORMABLE O-RING CARRIED IN SAID RECESS FOR ENGAGEMENT WITH THE INSIDE SURFACE OF THE BELL END OF AN ADJACENT PIPE; SAID BELL END INCLUDING A SOLID METALLIC CYLINDER SPACED INTERMEDIATE THE INSIDE AND OUTSIDE WALLS THEREOF. 